1. Field of the Invention
The present invention relates to a flat panel display device, and more particularly, to a flat panel display device that can prevent electrode disconnection due to a step difference between display and peripheral regions.
2. Description of the Related Technology
FIG. 1 is a plan view of a typical organic light emitting display device, and FIG. 2 is a cross-sectional view of the organic light emitting display device, taken along the line II-II of FIG. 1.
As depicted in FIGS. 1 and 2, the organic light emitting display device includes a substrate 10 which includes a display region 20, a peripheral region surrounding the display region 20, and a terminal region 70 outside the peripheral region. The display device further includes a sealing member which is configured to enclose the display region 20 and the peripheral region. The sealing member includes a metal cap 90 and a sealant 81.
The display region 20 includes a plurality of display pixels arranged in a matrix form and a plurality of driving lines VDD31 connected to the pixels. The display pixels include thin film transistors and organic light emitting devices or diodes (not shown). The peripheral region includes an electrode wire unit 41, a driving power wire unit 30, a vertical circuit unit 50 and a horizontal circuit unit 60. The terminal region 70 includes electrodes via which power and input signals are supplied from external devices.
The display device further includes a facing electrode 40 which electrically connects the organic light emitting devices to the electrode wire unit 41. The electrode wire unit 41 is electrically connected to the electrodes in the terminal region 70. In addition, the plurality of driving lines VDD 31 in the display region 20 are electrically connected to the electrodes of the terminal region 70 via the driving power wire unit 30. The driving lines VDD 31 supply driving power to the display region 20. The vertical circuit unit 50 and the horizontal circuit unit 60 are electrically connected to the electrodes in the terminal region 70 via the circuit wire units 51 and 61, respectively. The circuit units 50 and 60 supply input signals to the thin film transistors in the display region 20.
In the structure described above, a plurality of thin film transistors are included in the display region 20, the vertical circuit unit 50, and the horizontal circuit unit 60. A protection or passivation layer is formed over the thin film transistors for protecting the transistors and for providing a horizontally planar surface over the transistors. The protection or passivation layer is formed in one body, covering the display and peripheral regions of the substrate 10. The protection or passivation layer is typically a composite film formed of organic and inorganic materials.
Typically, the protection or passivation layer generates a gas which is detrimental to certain display device elements, such as the organic light emitting devices in the display region 20. In addition, impurities tend to penetrate into the display region 20 through the protection or passivation layer, thereby further degrading display device elements in the display region 20.